From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [edk2] apparent SMBASE relocation issue with noexec enabled [was: MdeModulePkg DxeIpl: Add stack NX support] Date: Fri, 7 Aug 2015 12:38:34 +0200 Message-ID: <55C48AAA.80001@redhat.com> References: <1438345360-7076-1-git-send-email-star.zeng@intel.com> <55C22EC0.2030400@redhat.com> <43260721-AB29-4182-8961-D33A70C5377B@apple.com> <55C23994.4000804@redhat.com> <0C09AFA07DD0434D9E2A0C6AEB04831002175554@shsmsx102.ccr.corp.intel.com> <55C31D59.6060400@redhat.com> <0C09AFA07DD0434D9E2A0C6AEB04831002175A03@shsmsx102.ccr.corp.intel.com> <55C36446.1030904@redhat.com> <55C36FB3.2040602@redhat.com> <55C3755D.4000408@redhat.com> <55C3E1E1.70504@redhat.com> <55C3E777.5070102@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: "edk2-devel@ml01.01.org" , KVM devel mailing list , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= To: Laszlo Ersek Return-path: In-Reply-To: <55C3E777.5070102@redhat.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: edk2-devel-bounces@lists.01.org Sender: "edk2-devel" List-Id: kvm.vger.kernel.org On 07/08/2015 01:02, Laszlo Ersek wrote: >> > The trace covers the full lifetime of the guest (I started tracing >> > before launching the guest, and I passed -no-reboot to qemu, so when the >> > guest crashed, QEMU exited.) >> > >> > This was on 3.10.0-299.el7.x86_64. > I repeated the test with EPT off. The guest doesn't crash this way, it spins in a busy loop. > > qemu-system-i38-32767 [002] 55142.911133: kvm_emulate_insn: 0:7ffd790b: 0f aa > qemu-system-i38-32767 [002] 55142.911139: kvm_cpuid: func 80000001 rax 6e8 rbx 0 rcx 0 rdx 100000 > qemu-system-i38-32767 [002] 55142.911148: kvm_enter_smm: vcpu 0: leaving SMM, smbase 0x7ffc0000 > qemu-system-i38-32767 [002] 55142.911150: kvm_mmu_get_page: existing sp gfn 7fe65 1/2 q3 --- !pge !nxe root 0 sync > qemu-system-i38-32767 [002] 55142.911151: kvm_mmu_get_page: existing sp gfn 7fe66 1/2 q3 --- !pge !nxe root 0 sync > qemu-system-i38-32767 [002] 55142.911151: kvm_mmu_get_page: existing sp gfn 7fe67 1/2 q3 --- !pge !nxe root 0 sync > qemu-system-i38-32767 [002] 55142.911151: kvm_mmu_get_page: existing sp gfn 7fe68 1/2 q3 --- !pge !nxe root 0 sync > qemu-system-i38-32767 [002] 55142.911152: kvm_entry: vcpu 0 > qemu-system-i38-32767 [002] 55142.911152: kvm_exit: reason EXCEPTION_NMI rip 0x7ffdb6b2 info 7fe88760 80000b0e > qemu-system-i38-32767 [002] 55142.911153: kvm_page_fault: address 7fe88760 error_code b > > And then the last triplet is repeated infinitely. > > 0x7ffdb6b2 is the address of the same first instruction executed after the RSM. > > The address 0x7fe88760 seems to fall into an EfiBootServicesData allocation, made in PEI (via a suitable HOB): > > Memory Allocation 0x00000004 0x7FE69000 - 0x7FE88FFF You probably should use "-cpu model,-lm,-nx". EFER is not part of the 32-bit state save map, so the EFER.NXE bit is not restored correctly on exit from SMM if you emulate a 32-bit CPU. I have not debugged yet why it works without KVM, nor why the symptoms are different between EPT and non-EPT. Paolo